1. Field of the Invention
The present invention relates to stabplate connections.
2. Description of the Prior Art
Electric and hydraulic power, chemical injection and communications are typically transmitted to subsea wells via an umbilical from a surface or land based platform, the umbilical being terminated at an umbilical termination assembly (UTA). The feeds for hydraulic power and chemical injection are effected from the UTA to a well tree, which houses a well control system, by a multiplicity of self-sealing individual connectors. In order to facilitate mating or unmating of the hydraulic power and chemical injection connectors subsea by a remotely operated vehicle (ROV), they are typically mounted together on a plate known as a stabplate, so that a single ROV action mates all the connectors. Such a stabplate arrangement is normally reserved for the hydraulic power and chemical injection feeds to the well. The ROV locates the stabplate to a fixed reciprocal plate mounted on the subsea tree, and, typically, a screw mechanism is operated by the ROV to force the two plates to mate and to lock them together. The mating and locking screw mechanism is, typically, part of the stabplate connection and remains subsea during the operation of the well. Unmating of the stabplate connection for maintenance/repair purposes involves an operation by an ROV of unscrewing the screw mechanism, which is designed to force the mated plates apart.
The main problem with the arrangement described above is that leaving the screw mechanism subsea for lengthy periods of time can result in corrosion and contamination (e.g. biological growths) which can cause the screw mechanism to seize. The result is either the need for other forceful methods of separating the stabplate from the fixed plate (invariably resulting in expensive damage to the well tree and parts of the stabplate connection) or the additional cost of including a secondary release mechanism in the design of the stabplate connection.